October i8, 1894] 



NA TURE 



595 



the surface of the fruit. Unfortunately the fruit is isolated, and 

 affords no clue as to the nature of the organ to which it was 

 originally attached. Numerous thin lamellce occur in associa- 

 tion with the seminiferous peduncles ; to these Lignier has 

 applied the term interseminal scales. The seeds are arranged 

 side by side close to the upper surface of the mass of peduncles 

 and interseminal scales ; the latter pass between and beyond 

 the seeds, and their swollen distal ends form a protective 

 covering to the blunt hemispherical apex of the fruit. In 

 surface view, the upper part of the specimen appears to be 

 made up of a large number of small projecting areas with 

 polygonal bases and rounded summits. Here and there the 

 projections arrange themselves in the form of rosettes round a 

 small central cavity, marking the position of a seed. 



luvolucral Bracts. — .Some important facts have been brought 

 to light as the result of a detailed histological examination of 

 these structures by means of a series of transverse sections. In 

 section each bract has the form of an isosceles triangle with the 

 base directed towards the surface of the fruit. The excellent 

 preservation of the tissues affords indisputable evidence of the 

 existence of stomata and numerous laiuellar epidermal out- 

 growths, similar to certain structures described byCarruihers in 

 B. Gibsoiiiaitus. The most interesting part, perhaps, of 

 Lignier's account of the bract tissue, is the inference he draws 

 from an examination of the course and structure of the several 

 vascular strands traversing each bract. It would seem that the 

 vascular bundles are (ar from their termination, and that the 

 involucral bracts as shown in the specimen are merely the 

 petiolar portions of leaf-structures, of which the pinnate or 

 flabellate laminae have not been preserved. Immeiiately 

 underneath one of the scaly hairs of an involucral bract a 

 section has cut through what is apparently a lenticel ; in this 

 case, suggests Lignier, lenticel development has probably taken 

 place as the result of irritation consequent on the fall or decay 

 of a hair. 



Seed-bearing Ptduiicles. — The main portion of the fruit itself 

 is made up of well-developed peduncles having a length of 

 30-.-J5 mm., and a diameter of I'j mm. Each peduncle con- 

 sists of fundamental tissue traversed by a single axial bundle, 

 and surrounding the whole there is a very characteristic 

 epidermal laver, which is gradually replaced towards the upper 

 part of the fruit by a ** tubular envelope '" of variable thick- 

 ness. This change is probably the result of the elongation of 

 the peduncles, and of the epidermal cells which mcreased 

 in length without undergoing transverse division, and thus 

 became transformed into tubular elements. A similar alteration 

 of epidermal cells occurs in B Cibsoniauus, but in that species 

 its true nature was apparently not recognised by Carruthers 

 and Solms-Laubach. 



Seeds. — Each peduncle terminates directly in an orthotropous 

 seed with a single integument ; the seeds are elliptical below, and 

 assume a tetragonal or pentagonal form towards their apices. In 

 the neighbourhood of the seeds, the tubular envelope of the 

 peduncles is reduced in size, and becomes differentiated into a 

 small tubular, and a folded layer of cells. The former is pro- 

 longed to the apex of the seed : the latter retains its special 

 character in the lower half, but towards the upper half of the i 

 seed its cells become radially elongated, and give place to 

 a tissue described as the "assise r.-iyonnante." Passing up to 

 the micropylar canal the two layers undergo a further modifica- 

 tion ; the tubular envelope has now assumed the rMc of an 

 ordinary epidermis, and the "assise rayonnante" passes into a 

 simple subepidermal layer of cells. The inner face of the 

 micropyle consists of narrow and radially elongated elements, 

 which become isodiametric as we pass down to the pollen- 

 chamber. The fundamental tissue of the seed-coat is divided 

 into an external fleshy and an internal fibrous portion. In de- 

 scribing the cells of the fleshy part of the integument, Lignier 

 points out that the thin cell walls show here and there numerous 

 tine pits, and the cell cavity contains a dark substance which 

 may possibly represent the remains of protoplasmic and other 

 cell contents. In some cases the contracted protoplasm (.v/i ) 

 shows slender prolongations which appear to correspond to the 

 pits in the cell wall ; these are interpreted as strands which 

 originally traversed the cellulo.se walls, and connected cell with 

 cell. It is perhaps questionable how far the tissues of fossil 

 plants will stand the strain of the minute descriptions which 

 characterise the work of some Krench writers ; but if proto- 

 plasmic continuity can be thus partially demonstr.ited in a fossil 

 seed, it suggests possibilities beyond the wildest dreams of paljEO- 



vo. 1303, VOL. 50I 



botanical histologisis ! The greater part of the nucellus is oc- 

 cupied by a large embryo with two cotyledons. On the whole, 

 the general disposition of the peduncles and seeds is the same 

 as in B. Gibsonianus, but various differences in detail sufficiently 

 establish a specific difference. 



Interseminal Scales. — These may be compared to the scales 

 in a pine cone ; they are associated with the seminiferous 

 peduncles, but extend beyond them, and form a continuous pro- 

 tective layer at the exposed surface of the fruit. External to 

 the interseminal scales there are the so-called superficial scales, 

 which have a fairly definite structure, and are not to be con- 

 founded with the external involucral bracts. 



The above imperfect r.'jHr/;,' conveys but a poor idea of the 

 thorough and careful treatment of the fossil at the hands of 

 Prof. Lignier. 



In his concluding remarks as to the nature of B. Morierei, 

 the author of the monograph expresses himself somewhat as 

 follows : — Regarding the supporting trunk as an axis of the 

 first order, the fruit-bearing axis is of the second order, and has 

 its apex contacted in the form of a convex receptacle ; the 

 leaves below the receptacle are transformed into involucral 

 bracts, the leaves inserted on the receptacle itself have become 

 interseminal scales, and the seed-bearing peduncles are fertile 

 leaves belonging to unileaved shoots of the third order. 



The inflorescence of Bcnncttites is clearly distinguished from 

 that of the Cycads in the following points: — (i) Ovules are 

 terminal and erect ; (2) each fertile bud is of a higher order 

 and much reduced ; (3) the inflorescence is compound, formed 

 by the grouping together of several fertile shoots, with a sup- 

 porting branch and its leaves, &c. " The Bennettitea are there- 

 fore posterior to the Cycadce, at least as regards the repro- 

 ductive structures." 



On the other hand, the inflorescence of Benneltitcs presents 

 many points of agreement with the Coniferce ; e.g. in its com- 

 pound nature, small seeds, unileaved fertile shoots with erect 

 ovules, &c. The points of difference between Bcnncttites and 

 the Coni/em include (i) larger number of sterile leaves asso- 

 ciated with the single-leaved buds; (2) the position of the 

 fertile shoots, which is not perhaps strictly axillary, &c. 

 Summing up the whole matter, Lignier says : — " I regard the 

 lUiinetlitcir as a family which has been derived with the Cycads 

 from common ancestors, but not from the Cycads themselves. 

 Of these cominon ancestors the two families have preserved the 

 form of the trunk, the structure of certain tissues (large pith, 

 gum canals, diploxyloid leaf-traces, and sclerenchymatous 

 mesophyll), the foliar origin of the ovule, &c. But whil.st the 

 Cycads have retained a grouping of carpophylls on a single 

 axis, and have acquired special characters, such as the com- 

 plication of the leaf-trace and the lateral position of the ovules ; 

 the BeniiettitCiC have retained the simple leaf-trace and have 

 .acquired a terminal position of the ovules, the reduction of the 

 fertile axes to a single corpophyll, the grouping of these fertile 

 reduced axes, and the modification of the neighbouring leaves 

 as the result of prcmrreuce sc.xuclle.^ Perhaps the future 

 will bring to light a greater affinity than is at present suspected 

 between the Bcnnettite^c and certain fossils referred to the 

 Cordaitea:." A. C. Seward. 



Science Teaching in St. Mary's Hospital Medical 

 School. 



My attention has just been called to an article in the 

 issue of Nature of September 20, headed " .Science in the 

 Medical Schools." This article professes to demonstrate by 

 means of a table, compiled from lists given in the students' 

 number of the Lancet, the extent to which instruction in science 

 subjects net purely medical is provided in the medical schools. 

 .■\ccording to this table, no instruction is provided in biology or 

 zoology, botany, physics, practical physics, bacteriology, and 

 hygiene, or public health, in this medical school. If you will 

 refer to the prospectus of the medical school, which I forward 

 with this letter, you will find that very complete courses of in- 

 struction are given in all those subjects here, and that the 

 instruction includes lectures, classes, demonstrations, and 

 laboratory work in all the subjects. 



* In explanation of this trrm Lignier adds : — " Jc dd-signe sous Ic nom dc 

 pn'ctirrcncc sc.vrtfttc Ic phenomLne par leipiel certains ortjanes soil porteurs 

 de la glande scxutie soil voislns dc ccllc-ci et formes .inlerieurcment \ cllc. 

 sont pcu ;t peu enploWs dans I'apparcil scxuci .-i mcsure que cclui-cise com- 

 plique dans la gi-nealogic des plantes. La prticurrcncc sexiielle ainsi 

 comprise sc rcnconire partout dans le rc^ne vegetal." 



